1. Field of the Invention
The present invention relates to a liquid spray device, more particularly to a liquid spray device for use in pleural inhalation therapy.
2. The Prior Arts
A liquid spray device is generally used in pleural inhalation therapy, such as asthma, includes a container for receiving a liquid medicine, which is sprayed out in term of a plurality of mist droplets. It is noted that the mist droplets should have a MMAD (mass median aerodynamic diameter) size smaller than 5 μm, only then the mist droplets can be breathed in or swallowed through the bronchioles in a human lung. The mist droplets sprayed out from the available liquid spray device should contain 50% of uniform droplets, each having a MMAD size less than 5 μm so as to permit these droplets to be breathed in by a patient or else result in waste of the liquid medicine. The known filter employed in the available spray device produces qualified and non-qualified mist droplets for the patient, thereby resulting in ineffective control of the given dose of liquid medicine to each patient.
In addition, a majority of the mist droplets sprayed out from the conventional liquid spray device fade away in the air, only a small amount of the mist droplets is breathed in by the patient concerned. Hence, the spilled or unused mist droplets cause environment pollution and waste of liquid medicine and exposing the healthy people to breathe the undesired mist droplets of liquid medicine.
U.S. Pat. No. 6,629,646 discloses a fluid injection device for ejecting fluid droplets in response to electrical signals comprises: an oscillating surface that has one or more tapered apertures, each aperture having a first and second opening. The first opening of each aperture is larger than the second opening. The first opening is in surface tension contact with the fluid to be ejected. The fluid interaction with the tapered aperture wall creates cycles of fluid compression and decompression inside the aperture, causing fluid to be drawn from the large opening and ejected out the small opening of the aperture. The device further includes a fluid supply nozzle that transports fluid to the oscillating surface at the larger opening of the aperture. A discharge valve controls the fluid supply. An electronic wave generator induces oscillation in the tapered aperture surface.
Another U.S. Pat. No. 6,863,224 discloses a liquid atomizing device including a bottom unit having a bottle section reserving a chemical liquid; a horn oscillating member to whose a distal end the liquid in the bottle section is fed; and a mesh member having a number of fine pores and mounted to an end surface of the distal end of the horn oscillating member in contact therewith. The bottle section is constituted of a large capacity section and a small capacity section in communication with the large capacity section through an opening opposing to the distal end. The small capacity section is formed such that the liquid is in contact with a point in the proximity of the contact section between the distal end of the horn oscillating member and the mesh member. The fluid dispensing operation is conducted without a special liquid feed means.
German Patent No. 102009001867 discloses a spray device including a driving unit for generating an oscillating energy; a polymer layer consisting of a plurality of apertures distributed at the bottom of the driving unit for generating fluid cycle in response to the oscillating energy, a tapered transmitting member connected to the polymer layer and having an opening corresponding to the apertures in the polymer layer, a circular oscillation member coupled electrically to the transmitting member for providing oscillation so that the liquid medicine on the polymer layer is sprayed out in form of micro mist droplets upon activation of the oscillation member.
In the above mentioned spray devices for pleural inhalation therapy, whether a metal mesh member is fixed and vibrated through the ultrasonic oscillator, as disclosed in U.S. Pat. No. 6,863,224, an alloyed micro sorter member is vibrated by ultrasonic metal ring (spray module), as disclosed in U.S. Pat. No. 6,629,646, or vibration of the polymer layer by the circular oscillation member, as disclosed in German patent No. 102009001867, to create a plurality of mist droplets depend on the aperture size and configuration of the filter member. Hence, the dimension of the plurality of mist droplets ranges from 0.5 ↑m to 50 μm. However, for the bronchioles of the human lung to breathe therethrough, the standard size of the mist droplets MMAD should be smaller than 5 μm and the mist droplets should occupies about 50% of the sprayed liquid. The abovementioned spray devices have the following disadvantages:
(a) In order to produce the mist droplets smaller than MMAD 5 μm, the micro pores in the mesh member should have a diameter equivalent to or less than 5 μm. It is expensive to construct the mesh member with less than MMAD 5 μm micro pores.
(b) Since only the mist droplets with less than MMAD 5 μm are breathed in by the bronchioles of the human lung, the remaining mist droplets vanish in the air, thereby causing waste of liquid medicine and resulting in insufficient of breathed in mist droplets of liquid medicine by the patient.
(c) Scatter of the mist droplets with greater than MMAD 5 μm in the air creates environmental pollution, which, in turn, can cause water pollution.